Microsoft has retreated from a core update practice for System Center, saying it is dropping Semi-Annual Channel (SAC) feature upgrades for the vendor's enterprise suite of client and server management tools.

Instead, System Center 2019 – the next iteration of the toolset, slated to ship later this month – will be available only as a Long-Term Servicing Channel (LTSC) release.

Microsoft said it's changing when System Center is refreshed "to optimise the way we are delivering new features."

SAC and LTSC are terms in the release cadence Microsoft has adopted for much of its software, including Windows, Windows Server and System Center.

SAC releases, which default to a twice-a-year schedule, provide new features and functionality to the base software, and are supported for a limited time, typically 18 months. However, one of the year's Windows 10 Enterprise SACs is supported with security updates for 30 months, an alteration Microsoft made in September 2018.

Meanwhile, LTSC releases are feature static, and are serviced with security and non-security bug fixes only; the support cycle runs the once-traditional decade, with the first five years labeled "Mainstream" and the second five tagged as "Extended."

A year ago, Microsoft announced the first SAC for System Center, dubbing the feature upgrade 1801 in the firm's yymm numeric format.

Six months later, Redmond rolled out System Center 1807. Each was assigned 18 months of support; 1801's final update will appear 8 August, while 1807's last will be issued 24 January 2020.

"The Semi-Annual Channel is for customers who innovate quickly," Microsoft asserted in a mid-2018 support document on System Center release options. "With approximately two releases a year, you get new enhancements, features, and fixes almost as soon as Engineering signs off."

But with last week's news, SACs are out.

"From talking to customers, we learned that LTSC works better for most System Center deployments as the update cycles are longer and more stable," wrote Vithalprasad Gaitonde, a principal program manager, as he repudiated the pitch Microsoft made the year before.

"Most of our customers use Long Term Servicing Channel (LTSC) like System Center 2016 to run their data center infrastructures."

Under the old model, new features and functionality were added to System Center gradually through the twice-annual SACs. Every two or three years, the accumulated features would be designated as a new LTSC build and given a new numeric label - that's how System Center 2019 came to be.

That process should sound familiar: It's how Microsoft assembles Windows 10's LTSC and the perpetual license form of Office.

Going forward, Microsoft will instead deliver the bulk of new System Center features every few years with the next LTSC release. Some new features will appear in what Microsoft called "Update Rollups," which have been used so far as cumulative collections of enhancements and bug fixes.

The Update Rollups will be offered approximately every six months and only during the five years of Mainstream support.

So is the SAC pull-back a harbinger of major changes in other Microsoft products' release strategy? Wes Miller, an analyst at Directions on Microsoft, doesn't think so.

"System Center as a whole is primarily used as data management," Miller said in an interview, referring to servers, not client devices. "So this makes a ton of sense (because) those customers have not come around to the SAC-style release cadence."

Yet he discounted the idea that killing SAC for System Center is the beginning of the end for the rapid release model. Miller cited System Center Configuration Manager (SCCM), aka "Config Manager," to make his case.

"Config Manager is focused on client management," Miller said, noting that Microsoft had not restructured that tool's release cadence. Config Manager will continue to receive feature upgrades three times a year. For some reason, Config Manager has preserved the pre-SAC terminology of "Current Branch" for each release.

Config Manager will retain the frequent upgrade process, Miller argued, because the software, unlike Windows Server, profits from the pace. "The previews have been phenomenal," Miller said, and that has made for happy customers.

Microsoft said that customers running System Center 2016 as well as the two SACs – System Center 1801 and System Center 1807 – will be able to upgrade to System Center 2019 when the latter launches.

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